ICN does have transit tours - similar to SIN but they do charge. This is the site that has the options - http://english.tour2korea.com/03Sigh...m=m3_4&konum=1 . We took the city tour in 2/06 and it was pretty good including the lunch provided. The tour desk can be pretty hard to find since its near the "security re-check" area for transit passengers so if you've gone through security you have to return back down an elevator and they'll probably ask what you're doing there - just say that you are checking on the Transit Tour and they'll let you through.